The present invention relates to wheels, and more particularly to a wheel assembly for an internal combustion engine providing a laminated cam and cam gear mounted on a camshaft.
Small internal combustion engines, such as those used on lawnmowers and snowblowers, generally include a cam gear and at least one cam mounted on a camshaft. The camshaft is rotated by means of the cam gear, which, as is conventional, meshes with a timing gear on a crankshaft to rotate in timed relation to the engine cycle. The cam may be used to control either an exhaust or an intake valve, as is also conventional.
In the past, such cams and cam gears have been formed utilizing time consuming and expensive precision machining methods. For example, such cams and cam gears are generally made by utilizing a hobbing machine to cut the gear or cam from a solid piece of metal. Hobbing cams and cam gears may also result in undesirable high waste or scrap material which further increases their cost of manufacture.
For some applications gears may be stamped from a metal blank by utilizing a punch and die arrangement. This process, however, is limited in the thickness of material that may be used, and by the strength of the material that is being used.
It is also known to use a gear formed of a laminated stack of thin gear elements, as shown in U.S. Pat. Nos. 3,999,445, 3,988,942, 2,516,365 and 1,481,212. In each of the above patents, however, the individual laminations of the gear are secured together to form a unitary structure by means of bolts, spot welds or adhesives. Such securing means not only increases the weight of the gear and thus its operational noise, but also adds to the cost of the structure.
A need has thus arisen for a cam and a cam gear structure that can be accurately produced by inexpensive stamping methods which would provide less scrap material, quieter operation and longer service life.
Various manufacturing processes are also known for assembling a camshaft, cam gear and cam. One such process involves mechanically forcing-in or pressing-in these components. However, manufacturing tolerances between the outer diameter of the camshaft and the inner diameter of the cam gear and cam may result in an improper fit. Thus, if the tolerances are too tight the cam gear or cam may crack or break during assembly, and if the tolerances are too loose the cam gear or cam may be loose on the camshaft.
It is therefore desirable to provide a mechanism that compensates for manufacturing tolerances of the components during assembly to securely mounted the components together without damaging the components during assembly.